Development of a Novel HPLC Method for the Analysis of Impurities in Meropenem and Identification of Unknown Impurities by 2D LC-IT-TOF MS

A novel stability-indicating HPLC method for the quantitative determination of impurities in meropenem raw material was established and fully validated for the further improvement of the official monograph in Pharmacopeia. The method was carried out on a Shim-Pack CLC-ODS column with UV detection at 220 nm. The influences of different band columns, composition ratio of mobile phase, gradient elution procedure, and pH value of mobile phase on separation of impurities in meropenem were investigated. The parameters specificity, precision, linearity, range, accuracy, limit of detection, limit of quantitation, and robustness were studied according to the regulatory guidelines recommended by the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH). The linear regression analysis results of EP impurity A and EP impurity B show that there is a good linear relationship between response and concentration, and the correlation coefficients are 0.9999 and 1.0000, respectively. The accuracy of EP impurity A and EP impurity B is between 90 and 104%. Through analysis, the LOD and LOQ values of EP impurities A and B were measured and found to be 0.22 and 0.74 µg mL-1, respectively. Moreover, three unknown degradation impurities in meropenem were identified by two-dimensional liquid chromatography tandem with high-resolution ion trap/time-of-flight mass spectrometry in electrospray ionization mode. Compared with the current method in Pharmacopeia, the developed method had greatly improved the separation and detection ability of impurities. The established method was highly specific, sensitive, and accurate for reliable routine quality control of meropenem raw material. The structures of unknown impurities were characterized based on the MS/MS data.